First, install wget and download the script by using pkg install wget && wget https://raw.githubusercontent.com/NotteShock/TermuxArch-XFCE/main/archxfce4 && chmod +x ./archxfce4 && ./archxfce4

Just wait for the script to download necessary things for you. After that type vncserver :1 and voilà, you will get a XFCE environment

If you already installed:

Run ./on and you successfully booted up the XFCE environment.